1. Field of the Invention
With the rising costs of fuel for internal combustion engines and the growing concern over pollution of the environment, it is now generally recognized that the venturi-float chamber type of carburetor does not provide either the precise control of fuel-air ratio, the fine atomization or the uniform mixture for optimum results. Many refinements have been added, and some of the faults reduced, but in turn the structure has become more complicated and sensitive, while retaining major shortcomings. Multiple barrels have been incorporated to increase performance under load, while maintaining economy at low speeds. The net results have been a more complicated device considerably short of the ideal.
One proposed solution has been the electronically controlled fuel injection system. Here the air volume entering the intake manifold is measured, often by sophisticated means, corrected for temperature and pressure variables, and this data together with other such as engine speed and torque requirements fed into a computer type of electronic control. Fuel is supplied under pressure to nozzles where needle valves time and control fuel flow under direction of the electronic system. Needle opening may be less than a thousandth of an inch for a micro second. It has been reported that such systems are to be offered on American cars in the future at a cost of several hundred dollars additional. There is little in the official tests reports to indicate they substantially increase mileage or decrease pollution.
Another means suggested for achieving more accurate air-fuel ratios is to measure air flow to the manifold by passing it thru a venturi and using a transducer to measure volume by the degree of pressure drop or variation of flow pattern. This is then corrected for pressure and temperature, engine speed, torque, etc. and the resulting computation used to feed a continuous stream of fuel to an ultrasonic atomizer which discharges into the air stream going to the intake manifold. None of these systems offer the precise control of air-fuel mixture so important to meet the standards for economy and clean air currently being discussed, and they introduce service problems beyond the scope of the average vehicle mechanic.
It would also seem probable at the current state of the art that some sort of stratified charge engine, particularly if a simple dual ratio fuel system were available, would be the simplest and most effective way to provide both maximum fuel economy and meet clean air standards. Stratified charge require two separate air-fuel ratios - one which has excellent ignition characteristics, and another which is normally much leaner, but preferably should vary its mixture to meet torque demands on the engine. To meet these requirements, fuel injection systems become extremely complicated, and if the venturi-float chamber system is used, either two separate carburetors as in one successful car, or two separate venturis built into one housing would be necessary. A simple device to provide both mixtures in precise ratios with fine uniform mixture would be most helpful.
2. The Prior Art
There is a vast prior art on means of mixing fuel with air to furnish an explosive mixture for internal combustion engines. Almost exclusively these relate, however, to devices of the venturi-float chamber design or fuel injection systems of the basic diesel type which have been established in fundamental principle for almost a century. Mostly these have to do with attempts to improve operating deficiencies of the structures. While the use of variable orifices have been long used for measuring fluids, particularly in laboratories, the structure disclosed here is believed to be unique as is its generation of power for modulating a metering pump. Details of the pump are shown in De Lancey U.S. Pat. No. 2,409,477, and similar pumps were widely used for decades on air atomizing oil burners. The principle of atomizing liquid by contact with a high speed disc has likewise been long and successfully employed in the oil heating industry.